What a 500-year-old latrine teaches us about human migration and the spread of disease

What was once a chute for both human and material waste in Jerusalem has now proven to be a store of new information about Christian migrants to the city, and the pathogens they brought with them.

After years of excavation in Jerusalem’s Christian quarter, archaeologists from the École Biblique uncovered a courtyard latrine of what was possibly a resting house dating back to the late 15th and early 16th centuries, when the city was under the control of the Mamluk Sultanate.

A recent study at the University of Cambridge analyzed 12 stool samples from the latrine, known as coprolites, and found six different intestinal parasites, preserved within the fecal matter. While many of the parasites are known to have been native to the Middle East and Northern Africa, two of them – Entamoeba dysentery and fish tapeworm – were more common in Northern Europe.

Although the parasites themselves had long broken down and died, their eggs were preserved within the coprolites. The shapes and sizes of the eggs were distinct enough for researchers to identify the parasites that spawned them.

Researchers linked the fish tapeworms found in the Jerusalem latrine to the preparations methods for fish in Scandinavia, Germany and Britain as described in cookbooks of the era. Fish in that region were eaten either pickled, smoked or raw, allowing parasites to survive within the meat. Even though fish was consumed less often in the Middle East, it was cooked thoroughly enough to kill the tapeworms inside.

Piers Mitchell, a professor of biological anthropology at the University of Cambridge who co-authored the study, is a staunch advocate of paying close attention to the history of sanitation to understand disease. He says that this research is part of a growing patchwork of case studies that paint a bigger picture of historical epidemiology – the distribution of diseases over time.

“Once we’ve managed to fill in the gaps in the parts of the world we don’t know about ancient parasites, then we would be in a much better position to say where these species of parasites first evolved,” he told the PBS NewsHour. “So we’re pretty far away down that line, we’re pushing the boundaries of what we know.”

According to Mitchell, the historical map of which diseases have spread, which have died out and why has much to offer current policy.

“If you can look at the past, then you can look at the present. And then that can give us some guidance into what the future might be like,” he said.